Design for a Wall Monument, ca. 1490, Pen and brown ink, brush and brown wash, blue gouache, on vellum, 7 1/4 x 7 1/4 in. (18. 4 x 18. 4 cm), Drawings, Francesco di Giorgio Martini (Italian, Siena 1439?1501 Siena), Francesco di Giorgio was a Sienese sculptor, painter, illuminator, architect, and military engineer. The precise function of this drawing is uncertain; it may record an idea for a tomb sculpture or perhaps a painting